<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
</head>
<body>
<div id="app-3">
    <!--条件-->
    <p v-if="seen">现在你看到我了</p>
</div>

<script type="text/javascript">
    var app3 = new Vue({
        el: '#app-3',
        data: {
            seen: true
        }
    })
</script>
</body>
</html>
